Sheet conveyor roll jam up sensing apparatus

ABSTRACT

A roll jam-up sensing apparatus is described which may be used on sheet conveyor rolls, such as the pairs of upper and lower rolls used in a veneer dryer, such rolls being mounted in support brackets which enable upward movement of the upper rolls when a jam-up occurs. A plurality of sensing devices each including a resilient actuator member, which is preferably in the form of a coil spring, are mounted on such support brackets so that the free end of the actuator spring contacts the upper roll or its shaft during such upward movement and thereby actuates a jam-up indicating means. The sensing devices are preferably electrical sensors each having an electrical terminal member which is connected to the fixed end of the actuator spring, and the free end of such spring is grounded upon engagement with the roll shaft to actuate a relay and associated signal light in the indicating means. The electrical terminal member is preferably a bolt threaded into the coil spring and supported within an aperture in a mounting plate by an electrical insulator sleeve releasably held by a set screw in such aperture.

United States Patent [191 Lewis Sept. 2, 1975 SHEET CDNVEYOR ROLL JAM UPSENSENG APPARATUS Primary ExaminerRichard A. Schacher AssistantExaminer-Bruce H. Stoner, Jr. Attorney, Agent, or Firm-Klarquist,Sparkman, Campbell, Leigh, Hall & Whinston [57] ABSTRACT A roll jam-upsensing apparatus is described which may be used on sheet conveyorrolls, such as the pairs of upper and lower rolls used in a veneerdryer, such rolls being mounted in support brackets which enable upwardmovement of the upper rolls when a jam-up occurs. A plurality of sensingdevices each including a resilient actuator member, which is preferablyin the form of a coil spring, are mounted on such support brackets sothat the free end of the actuator spring contacts the upper roll or itsshaft during such upward movement and thereby actuates a jam-upindicating means. The sensing devices are preferably electrical sensorseach having an electrical terminal member which is connected to thefixed end of the actuator spring, and the free end of such spring isgrounded upon engagement with the roll shaft to actuate a relay andassociated signal light in the indicating means.

The electrical terminal member is preferably a bolt threaded into thecoil spring and supported within an aperture in a mounting plate by anelectrical insulator sleeve releasably held by a set screw in suchaperture.

15 Claims, 4 Drawing Figures PATENTED 2 I975 FIG 36 TO OTHER RELA SHEETCONVEYOR ROLL JAM UP SENSING APPARATUS I BACKGROUND OF THE INVENTION Thesubject matter of the present invention relates generally to roll jam-upsensing apparatus and in particular to jam-up sensing apparatus forsheet conveyor rolls, such as the rows of-pairs of upper and lower rollsused in wood veneer dryers. The sensing apparatus includes a pluralityof sensing devices having resilient actuator members, preferably coilsprings, which engage the roll or roll shaft upon upward movement ofsuch roll when a jam-up occurs. In a veneer dryer the roll jam-up iscaused by a sheet of wood veneer curving up or down intoan adjacent rowof rollers out of the row of rollers attempting to convey such veneerhorizontally through the dryer.

Previously, roll jam-up sensing apparatus for veneer dryers haveemployed a plurality of long electrical wires which each extend acrossthe ends of a plurality of veneer conveyor rolls forming a horizontalrow or tier of rolls. This detector wire type of sensing device hasseveral disadvantages. Thus, such detector wire cannot be adjusted tocompensate for different spacing or positions of each roll. Also, itmust be completely removed or bent up out of the way in order for theoperator to clear the jam or to 'changea dryer roll for other purposes.Removal and replacement of the wire take too long a time, while aftersuch bending, the wire is not in the proper position to operateeffectively. Furthermore, this prior sensing apparatus is of lowsensitivity because such detector wires are held in straight lines abovethe top of the rolls, spaced from such rolls suffciently to preventengagement of anyv upper rolls except during jamup with the result thatthey must be positioned above the highest roll so that they are spaced agreater distance from the lower rolls in the tier of upper rolls.

The roll jam-up sensing apparatus of the present invention overcomesthese disadvantages by employing individual sensing devices for eachroll which may be mounted on the support brackets of each rollshaft. Thespacings between the sensing devices and the rolls may be individuallyadjusted which results in greater sensitivity for the sensing apparatus.This increased sensitivity enables the present sensing'apparatus tosense upward movement of the rolls before severe jam-up conditions existand enable the operator to avoid many jam-ups which would otherwiseoccur. Furthermore, by using a resilient actuator member, the presentsensing apparatus does not restrict upward movement of the rolls orinterfere with the removal of dryer rolls, such as when the operator isunjamming the veneer dryer by removal of the jammed wood veneer.

SUMMARY OF THE INVENTION It is, therefore, one object of the presentinvention to provide an improved roll jam-up sensing apparatus of highsensitivity and simple trouble-free operation which senses lateralmovement of the rolls when ajamup occurs.

A further object of the invention is to provide such a sensing apparatuswhich enables easier roll maintenance including removal of the rollswithout removal or damage to the sensing apparatus.

Another object of the invention is to provide such a sensing apparatusfor sheet conveyor rolls, such as are used in a veneer dryer, includinga plurality of individu' ally adjustable sensing devices which aremounted in position to sense upward movement of the dryer rolls withoutrestricting such upward movement.

A still further object of the present invention is to provide such asensing apparatus in which the sensing devices are of simple andeconomical construction and each include a resilient actuator member,such as a coil spring, which is not damaged by upward movement of theroll shaft which it engages.

Still another object of the invention is to provide such sensing devicesin the form of electrical detectors in which the coil spring actuatormember is attached at its free end to an electrical terminal and makeselectrical contact with its free end to the roll or roll shaft toactuate an electrical indicating apparatus.

Still another object of the invention is to provide such a sensingdevice in which the spacing between the free end of the coil spring androll or roll shaft is adjustable for earlier detection of upwardmovement of such roll shaft in order to prevent severe jam-ups.

BRIEF DESCRIPTION OF DRAWINGS Other objects and advantages of thepresent invention will be apparent from the following detaileddescription of certain preferred embodiments thereof and from theattached drawings of which:

FIG. 1 is a side elevation view of a veneer dryer em ploying thejam-upsensing apparatus of the present invention, with parts broken away forclarity;

FIG. 2 is an exploded enlarged view of one embodiment of a sensingdevice and associated pair of conveyor rolls used in FIG. 1, togetherwith a schematic diagram of the electrical circuit actuated by suchsensing device;

FIG. 3 is an enlarged section view taken along the line 3-3 of FIG. 2,showing the sensing device mounted on the roll support bracket; and

FIG. 4 is an enlarged section view similar to that of FIG. 3 showinganother embodiment of the sensing device.

DESCRIPTION OF PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2 the sheetconveyor roll jam-up sensing apparatus of the present invention includesa plurality of sensing devices 10 which are mounted adjacent to the endsof upper conveyor rolls 12. Each of the sensing devices includes aresilient actuator member 14 which senses the upward or other lateralmovement of the upper roll 12, such as by engagement with the roll orits shaft 16 during a jam-up. The upper roll 12 is rotationally mountedon shaft 16 in a U-shaped support bracket 18 which enables upwardmovement of the roll shaft as well as rotation thereof. A plurality oflower conveyor rolls 20 are mounted beneath the upper rolls T2 toprovide a plurality of roll pairs which convey the sheet materialbetween such upper and lower rolls. The lower rolls are eachrotationally mounted in annular bearings provided in support brackets 22which enables rotational movement of their shafts 24 but prevents upwardor any other lateral movement of such lower rolls. The lower roll shafts24 are all coupled to a common drive motor (not shown) in a conventionalmanner such as by a chain drive for rotating the lower roll 20, whilethe top roll shafts 16 are loosely coupled to such lower shafts by starwheel gearing (not shown) which enables upward movement of the topshafts.

The roll pairs 12 and 20 are positioned in horizontal rows of differentlevels in a veneer dryer and wood ve neer 26 is fed along suchhorizontal rows between the upper and lower rollers. Thus, the upperrolls are spaced from the lower rolls by the thickness of the veneer 26which will vary, and this variation is accommodated by lateral movementof the upper rolls in the U-shaped support bracket 18. The upper rollshaft 16 moves upward slightly in response to variations in thickness ofthe sheet material 26 and also when two sheets overlap. However, thesensing devices 10 are positioned so that their actuator springs 14 donot engage the upper roll shafts 16 under these normal operatingconditions, but only engage such roll shafts underjamup conditions.Typically such ajam-up occurs when the veneer 26 curls up or down intothe next adjacent horizontal row or tier of rollers, as shown in FIG. 1by the curved leading edge 38 on one veneer sheet. This causes the upperroller 12 immediately in front of the curved veneer section 28 to beraised upward by such veneer section as it is driven forward by theprevious rollers. Such upward movement of the roller 12 is sensed by theresilient actuator member 14 of the sensing device engaging the shaft 16of such upper roller and the sensing device 10 then operates a jam-upindicating means 36 as hereafter described.

As shown in FIG. 1, the veneer dryer has a plurality of separate dryerchambers including a first chamber 30 and a second chamber 32 set atdifferent temperatures which can be as high as 550 F. The veneer sheetmaterial is fed from one dryer chamber 30 to the next to gradually drythe veneer to the proper moisture content before discharge from thedryer. The veneer dryer apparatus will not be described in detailbecause it is conventional except for the presence of the jam-up sensingdevices 10 and their associated electrical circuit. All of the sensingdevices 10 in the first chamber 30 are connected through their actuators14 to a common control wire 34 which applies a suitable voltage of about6 volts DC. to such devices and connects these devices to the indicatormeans 36 to illuminate a first signal light 38 when the actuator 14 ofone of such sensing devices contacts an upper roll shaft 16. In asimilar manner all of the sensing devices 10 in the second dryer chamber32 are connected by their actuators 14 to another control wire 40 whichapplies 6 volts D.C. thereto and operates a second signal light 42 onthe indicator means 36.

As shown in PK]. 2 the indicator means 36 contains a plurality of relaysand associated signal lights each connected to one of the control wires34, 40, etc. For example when one of the sensing devices 10 in the firstchamber 30 is operated by its actuator spring 14 contacting the groundedroll shaft 16, current flows through the winding ofa relay 39 connectedin a series between a DC. voltage source 41 and all of the sensingdevices in chamber 30. This actuates the relay 39 and causes its movableswitch contact 43 to connect the signal light 38 to a source ofenergizing current suchas the 1 10 volts AC. power line shownv As aresult of illumination of the signal light 38, 42, etc, the operatorknows in which chamber of the dryer the jam-up situation is occurring,so that he can correct thejam-up condition more quickly. An audibleindicating device 44, such as a horn, may be provided on the indicatingmeans 36 and connected between the l 10 volts source and all the relaysfor Warning the operator of a jam-up when he is away from the indicatormeans. Alternatively, an automatic shut-off switch can be employed inplace of horn 44 for de-energizing the drive motor connected to therollers 20 of the dryer when a jam-up is sensed.

Jumper wires 45 are connected between each of the sensing devices 10 ina horizontal row or tier and also connect such devices to one of thecontrol wires 34 or 40. Thus, the sensing devices it) are connected inparallel through a control wire to the DC. voltage energizing source. Itshould be noted that the upper roll shafts 16 are grounded to themachine frame through bracket 18 and their star gear coupling to thelower roll shafts 24.

As shown in FIG. 3, one embodiment of the present sensing device 10provides a resilient actuator member 14 in the form of a coil spring 46of substantially uniform diameter having one end fixed to an electricalterminal 48 in the form ofa bolt which is threaded into the fixed end ofsuch spring. The electrical terminal member 48 extends through anaperture 50 in a mounting plate 52 of aluminum or other metal and iselectrically insulated therefrom by an insulator sleeve 54 of a suitablehigh melting point synthetic plastic such as polytetraflouroethylcne,known as Teflon, or a ceramic material. The annular sleeve is providedwith an annular groove 56 on its outer surface, and a set screw 58extends through a threaded hole in the top of the mounting plate 52 intoengagement with the groove 56 surface. Thus, the set screw releasablyholds the spacer sleeve 54 and the electrical terminal member 48 withinthe aperture 50 of the mounting plate 52. it should be noted that theset screw is positioned so that its axis does not pass through the axisof-the insulator sleeve 54 to prevent it from breaking a ceramic sleevewhile clamping it against the side of the aperture 50. A pair of locknuts 60 are provided between the head of the electrical terminal bolt 48and the insulator 54 in order to attach such bolt to connection wires45, such connection wires being provided with spade-shaped end terminalsof conventional type. A metal washer 62 is provided over the other endof the electrical terminal bolt 48 and engages the end of the coilspring 46 in order to clamp such bolt onto the insulator spacer 54between such washer and the inner nut 60 and its associated washer.

It should be noted that the spacing of the free end of the coil spring46 from the roll shaft l6 may be varied, either by clipping off aportion of such free end with wire cutters, or by rotating the bolt 48and the coil spring to move such free end toward and away from theshaft. Thus, the free end can either extend substantially perpendicularto the roll shaft 16 or may be in some other lateral position extendingat an acute angle to the axis of such shaft. Also, it is possible torotate the bolt 43 clockwise from the position in FIG. 2 so that thefree end of the coil spring will be engaged by the top of the roller l2upon upward movement of such roller.

Another embodiment of the invention is shown in HS. 4 and is similar tothat previously described, except that the sensing device 10 includes amodified actuator member 14' consisting of a'coil spring 64 having asmall diameter end threaded onto the electrical terminal bolt 48 andhaving a free end of larger diameter. The axis of the free end of spring64 is substantially coaxial with the axis of the free end, and extendsat least partially across the opening in the top of the support bracket18. In addition, a modified mounting bracket 52 is used and the spacersleeve 54 extends completely through such mounting bracket.

In the embodiment of FIG. 3, the spacer sleeve does not extendcompletely through the mounting bracket aperture 50, but terminatesabout in the middle of such aperture so that the bolt 48 is spaced fromthe right side surface of the mounting bracket 52. As a result, the coilspring 46 is not pressed against the edge of the aperture 50 by upwardmovement of the roller shaft 16 which otherwise might cut or damage thespring.

Both the mounting bracket 52 of FIG. 3 and the mounting bracket 52' ofFIG. 4 are attached to the top edge of the roll support bracket 18 by achanneled bracket portion 66 having a channel width equal to thethickness of the support bracket 18. In both cases, the mounting bracketis removably attached to the support bracket 18 by a clamping screw 68threaded through an opening in the outer side of the mounting bracket.

It will be obvious to those having ordinary skill in the art that manychanges may be made in the details of the above-described preferredembodiments of the present invention without departing from the spiritof the invention. For example, rather than electrical detectors, thesensing elements may be mechanical switches in which case the resilientactuating member 14 would operate the switch in the manner of a limitswitch. Of course such a mechanical switch would have to be providedwith high temperature insulating material to op erate in the environmentof a veneer dryer, and would be somewhat more expensive than the simpleelectrical sensing device 10. Therefore, the scope of the presentinvention should only be determined by the following claims.

I claim:

1. Jam-up sensing apparatus for a sheet conveyor comprising:

a plurality of sheet conveyor rolls having their normally rotatingshafts rotatably mounted in support brackets which enable upwardmovement of said rolls when a jam-up occurs;

a plurality of sensing devices each including a movable electricalcontact sensing member;

electrically actuable indicator means connected to said sensing devicesfor indicating when said jamuploccurs; and plurality of separatemounting means for separately attaching said sensing devices to saidsupport brackets with said movable electrical contacts of said sensingdevices normally spaced from but in position to electrically contact aportion of said rolls upon upward movement of said rolls to com plete anelectrical circuit between said indicator means and electrical groundthrough one of said movable electrical contact sensing members and oneof said rolls and thereby electrically actuate said. indicator means inresponse to the upward movement of one of said rolls without restrictingsaid upward movement.

2. Apparatus in accordance with claim 1 in which said movable electricalcontact is insulated from said mounting means by electrical insulationmeans.

3. Apparatus in accordance with claim I in which said movable electricalcontact is a resilient electrical contact which is insulated from saidmounting means by electrical insulation means.

4. Apparatus in accordance with claim 3 in which the resilientelectrical contact is a coil spring.

5. Apparatus in accordance with claim 3 in which the contact is a coilspring having a free end which is normally spaced from the roll shaftbut engages said shaft during said upward movement and having a fixedend connected to an electrical terminal.

6. Apparatus in accordance with claim 5 in which said support bracketshave upwardly open ends for enabling said upward movement of said rollsand the free end of said coil spring extends partially into the open endof said support bracket lateral to said shaft.

7. Apparatus in accordance with claim 5 in which said support bracketshave upwardly open ends for enabling said upward movement of said rollsand the free end of said coil spring extends at least partially acrossthe open end of said support bracket substantially parallel to saidshaft.

8. Apparatus in accordance with claim 1 in which the rolls are dryerrolls supported in a wood veneer dryer, said movable electrical contactis a resilient electrical contact, each of the mounting means includes amount ing bracket releasably attached to the support bracket supportingsuch dryer rolls and having an aperture through which said electricalcontact extends, and electrical insulation means of high meltingtemperature being provided between the wall of said aperture and saidcontact.

9. Apparatus in accordance with claim 8 in which the insulation means isan annular sleeve of electrical insulating material which is releasablyheld in said aperture by a set screw.

10. A roll jam-up sensing device comprising:

a resilient electrical contact sensing member;

an electrical terminal connected to said sensing member and extendingcoaxial with at least a portion of said sensing member;

mounting means for mounting said device adjacent to said roll with saidsensing member normally spaced above the normally rotating shaft of saidroll so that said sensing member is electrically actuated by electricalcontact with said shaft to complete an electrical circuit between saidelectrical terminal and electrical ground through said sensing memberand said roll in response to lateral movement of said roll during ajam-up without restricting said lateral movement; and

insulation means for electrically insulating said mounting means fromsaid electrical terminal and said sensing member.

11. A device in accordance with claim 10 in which the resilient sensingmember is a coil spring having a free end adapted to engage the shaft ofsaid roll and having a fixed end connected to said electrical termiha].

12. A device in accordance with claim ll in which said free end extendslaterally to the axis of said fixed end.

13. A device in accordance with claim H in which said free end issubstantially coaxial with said fixed end.

14. A device in accordance with claim ll in which said free end extendsout of an aperture in a mounting bracket and said fixed end is attachedto the electrical terminal within said aperture, and said insulationmeans is an insulator sleeve provided in said aperture around saidterminal to support said terminal in insulated relationship on saidmounting bracket.

15. A device in accordance with claim 14 in which said electricalterminal is a bolt having a threaded end screwed into the fixed end ofsaid coil spring.

1. Jam-up sensing apparatus for a sheet conveyor comprising: a pluralityof sheet conveyor rolls having their normally rotating shafts rotatablymounted in support brackets which enable upward movement of said rollswhen a jam-up occurs; a plurality of sensing devices each including amovable electrical contact sensing member; electrically actuableindicator means connected to said sensing devices for indicating whensaid jam-up occurs; and a plurality of separate mounting means forseparately attaching said sensing devices to said support brackets withsaid movable electrical contacts of said sensing devices normally spacedfrom but in position to electrically contact a portion of said rollsupon upward movement of said rolls to complete an electrical circuitbetween said indicator means and electrical ground through one of saidmovable electrical contact sensing members and one of said rolls andthereby electrically actuate said indicator means in response to theupward movement of one of said rolls without restricting said upwardmovement.
 2. Apparatus in accordance with claim 1 in which said movableelectrical contact is insulated from said mounting means by electricalinsulation means.
 3. Apparatus in accordance with claim 1 in which saidmovable electrical contact is a resilient electrical contact which isinsulated from said mounting means by electrical insulation means. 4.Apparatus in accordance with claim 3 in which the resilient electricalcontact is a coil spring.
 5. Apparatus in accordance with claim 3 inwhich the contact is a coil spring having a free end which is normallyspaced from the roll shaft but engages said shaft during said upwardmovement and having a fixed end connected to an electrical terminal. 6.Apparatus in accordance with claim 5 in which said support brackets haveupwardly open ends for enabling said upward movement of said rolls andthe free end of said coil spring extends partially into the open end ofsaid support bracket lateral to said shaft.
 7. Apparatus in accordancewith claim 5 in which said support brackets have upwardly open ends forenabling said upward movement of said rolls and the free end of saidcoil spring extends at least partially across the open end of saidsupport bracket substantially parallel to said shaft.
 8. Apparatus inaccordance with claim 1 in which the rolls are dryer rolls supported ina wood veneer dryer, said movable electrical contact is a resilientelectrical contact, each of the mounting means includes a mountingbracket releasably attached to the support bracket supporting such dryerrolls and having an aperture through which said electrical contactextends, and electrical insulation means of high melting temperaturebeing provided between the wall of said aperture aNd said contact. 9.Apparatus in accordance with claim 8 in which the insulation means is anannular sleeve of electrical insulating material which is releasablyheld in said aperture by a set screw.
 10. A roll jam-up sensing devicecomprising: a resilient electrical contact sensing member; an electricalterminal connected to said sensing member and extending coaxial with atleast a portion of said sensing member; mounting means for mounting saiddevice adjacent to said roll with said sensing member normally spacedabove the normally rotating shaft of said roll so that said sensingmember is electrically actuated by electrical contact with said shaft tocomplete an electrical circuit between said electrical terminal andelectrical ground through said sensing member and said roll in responseto lateral movement of said roll during a jam-up without restrictingsaid lateral movement; and insulation means for electrically insulatingsaid mounting means from said electrical terminal and said sensingmember.
 11. A device in accordance with claim 10 in which the resilientsensing member is a coil spring having a free end adapted to engage theshaft of said roll and having a fixed end connected to said electricalterminal.
 12. A device in accordance with claim 11 in which said freeend extends laterally to the axis of said fixed end.
 13. A device inaccordance with claim 11 in which said free end is substantially coaxialwith said fixed end.
 14. A device in accordance with claim 11 in whichsaid free end extends out of an aperture in a mounting bracket and saidfixed end is attached to the electrical terminal within said aperture,and said insulation means is an insulator sleeve provided in saidaperture around said terminal to support said terminal in insulatedrelationship on said mounting bracket.
 15. A device in accordance withclaim 14 in which said electrical terminal is a bolt having a threadedend screwed into the fixed end of said coil spring.